For those of you who haven't read it, it was an industry-sponsored trial comparing the most recent topical Epiduo (Adapalene/BPO) given together with Doxycycline against isotretinoin. The majority of authors are consultants, advisory board members or employees of Galderma.

Background Oral isotretinoin (ISO) is the gold standard for severe nodular acne. However, as some patients are unwilling or unable to take, or are intolerant to, ISO, other options are needed.Objectives To compare efficacy and safety of oral ISO vs. doxycycline 200 mg plus adapalene 0?1%/benzoyl peroxide 2.5% gel (D+A/BPO) in severe nodular acne over 20 weeks.Methods This was a multicentre, randomized, controlled, noninferiority investiga- tor-blinded study involving 266 subjects.Results D+A/BPO showed a significantly earlier onset of action in reducing nodules, papules/pustules and total lesions at week 2. ISO was superior in reducing nodules (95?.6% vs. 88.7%), papules/pustules (95.2% vs. 79.6%) and total lesions (92.9% vs. 78.2%; all P < 0.01) at week 20. Half as many subjects for D+A/BPO compared with ISO had treatment-related, medically relevant adverse events (33 events in 18.0% of subjects vs. 73 in 33.8% of subjects, respectively). D+A/BPO was noninferior to ISO in the intent-to-treat population [95% confidence interval (CI) .2.7 to 20.8 (P = 0.13); 63.9% vs. 54.9% of subjects, respectively] and per- protocol population [95% CI 3.9–28.6 (P = 0.01); 74.3% vs. 58% of subjects, respectively), based on the composite efficacy/safety end point.Conclusions D+A/BPO showed a favourable composite efficacy/safety profile compared with ISO. This combination is an alternative to ISO in patients intolerant to, or unable or unwilling to take, oral ISO, and is an option for treatment of severe nodular acne.

This study has several limitations including, in my opinion, a potentially biased interpretation of the data.

At the endpoint of the study, all relevant and achievable surrogates for acne intensity such as number of nodules, papules and pustules, total lesion counts, P. acnes fluorescence intensity and IGA (investigators global assessment) from baseline are clearly (and significant p < 0.05) better with isotretinoin than with D+A/BPO. Also, the curves are diverging towards stagnation in D+A/BPO and improvement in isotretinoin. Early on at 2 weeks however, the topical is a bit better in some measures, as might have been expected. The safety data is better with the D+A/BPO compared to isotretinoin.

The bias I perceived is introduced when the authors introduce a composite score of 16 safety measures and just 1 measure of efficacy (75% reduction of acne nodules). A statistical analysis based on those predefined efficacy/safety end points was done and somewhat surprisingly, the authors then conclude that from an efficacy/safety perspective, D+A/BPO treatment is not inferior to ISO (74.3% vs. 58% of success, respectively).

Some other limitations: The treatment groups forgo the possibility of observing independent effects of topical ADA+BPO, as it is combined with doxycyclin. However, there are references showing that combination of Epiduo with tetracyclines is better than tetracyclines alone. Also, the study was done in a 85% male population, making it difficult to conclude on effects in females.

So in conclusion, I think the authors may have had some vested interest to show that the topical is non-inferior to isotretinoin. Otherwise one could have chosen a composite score equally weighted for efficacy and safety.

Alex you are right on many (most) points BUT...this study if for me a key one because it provides data on "how much you can obtain" when Isotretinoin cannot be prescribed. Now you can( must ?) give up to 200mg/day for 20 WEEKS of doxycyclin plus a topical like Epiduo, but also any other, why not a retinoid like the old RetinA.It is brillant that Galderma dared financing such a study, and I think it paves the way for revisiting many topicals under the umbrella of the so well tolerated high dose long term doxy. We will recurrently hear about resistances, etc.. but a new field or a new front in the boring acne field.JHS

Both doxycycline and isotretinoin are used at high doses for prolonged periods:-doxycycline: the dosage is of 200mg for 20 weeks (over 4 months). I personally use doses of 100mg and the guidelines recommend a treatment duration of up to 3 months.-oral isotretinoin: in the study doses of up to 1mg/Kg/d are used which greatly increase the side effects.

Thanks for the post, it is always interesting to read about new studies in the acne field, especially comparative ones.

One of the major weakness of this study, in my opinion, is the deliberate choice of an endpoint at 20 weeks.

From what we all experience in the everyday clinical practice, I think that this 3 to 6 months period after initiation of treatment is often the period when we start to reach a plateau with cyclines, even with a high-dosis regimen like the one that was used in this study. In counterpart, especially with classical 0.5mg/kg isotretinoin therapies, it is often at the same time-period that we observe a dramatic increase in the clinical response of those under isotretinoin...

So it would have been interesting to see the results after 40 or 50 weeks... I assume the non-inferiority would surely be challenged...